28.01.2018 00:11
Launch the application and right-click on the empty area of Sources → Add → Video Capture Device (see pic. 1).
Give a name for your new capture device and ensure that Make source visible option is active. Then click on OK.
The properties window will appear. Select your webcam from the Device list and click on Activate if it is not yet. Click on OK and your webcam will be added to the workspace of OBS.
You can change a size of your webcam and apply some visual filters using Sources area.